The objective is to integrate regulation of lipid biogenesis in vivo with overall cell homeostasis, particularly the further association of lipids and proteins to in biological membranes. Kinetic tracer experiments are applied in vivo and in cell culture to determine turn - over rate and incorporation kinetics for individual lipid and protein components in intracellular membranes as well as the surface plasma membrane. Such data will permit evaluation of precursor - product relationships for individual components in different cell compartments. Such information is necessary as a foundation for any model membrane biogenesis.